JP5198709B2 - Method, apparatus and use for applying viscous media to a substrate - Google Patents

Abstract

A method of applying viscous medium on a substrate that is arranged for mounting of components includes providing the substrate arranged for mounting of electronic components thereon and screen printing predetermined amounts of a viscous medium on predetermined positions on the substrate. In addition, the method includes add-on jetting of predetermined additional amounts of viscous medium on predetermined positions on the screen printed substrate. The add-on jetting is non-contact dispensing and the add-on jetting viscous medium is still in viscous form during the add-on jetting.

Description

[0001]
(Technical field of the invention)
The present invention relates to the technical field of providing a viscous medium on a substrate. In particular, the present invention relates to a method for applying a viscous medium to a substrate, the method comprising a step of screen printing a predetermined amount of the viscous medium at a predetermined position on the substrate, and further to an apparatus for applying the viscous medium to the substrate, The apparatus relates to an apparatus that includes a screen printing unit that screen-prints a predetermined amount of viscous medium on a predetermined position of a substrate, and further applies an additional viscous medium to the screen-printed substrate.
[0002]
(Background of the Invention)
In electronic device production, the most common method of applying a viscous medium such as a solder paste to a substrate such as a PCB is to use screen printing. Most of the viscous media deposits can be applied in this way. However, in certain circumstances, different viscous media are required at different locations on the substrate. This causes problems. This is because there are some difficulties to overcome when adding viscous media by performing an extra screen printing procedure after the initial application of the viscous media. In addition, it may be desirable to generate a pattern of viscous media that is very difficult to achieve with screen printing, such as an empty circular pattern.
For example, to accommodate chip components with varying heights, components with varying lead angle accuracy, coplanar requirements, etc., the applied viscous media will have different heights at different locations on the substrate. It may also be desirable. A solution to the latter problem presented in the art uses so-called stepped stencils for screen printing. However, these stencils present several drawbacks that prevent the spread of this solution.
[0004]
Also, it is impossible to apply mainly circular, very small viscous media deposits, ie dots, by screen printing. This is because the adhesive force from the stencil becomes larger than that from the substrate. As a result, when the stencil is removed, very small deposits will adhere to and follow the stainless steel. It can be imagined that this problem can be overcome by thinning the stencil used. However, this reduces the overall height of the deposit, and thus the overall volume, which is undesirable and has the undesirable disadvantage of causing problems with relatively large deposits.
[0005]
According to the state of the art, efforts are made to solve the above-mentioned problems by using conventional dispensing equipment. By using a conventional dispenser, it is possible to add the viscous medium after first screen printing on the substrate to generate the pattern of viscous medium that is not easily achieved by screen printing. Conventional dispensers may also allow viscous media having different heights to be applied at different locations on the substrate. However, conventional dispensers have several drawbacks. The conventional viscous medium dispensing process is relatively time consuming, and it has been difficult to apply very small deposits of viscous medium with conventional dispensing, and at a position on the substrate already provided with the viscous medium, It is also difficult to apply additional viscous media.
[0006]
(Summary of Invention)
Accordingly, it is an object of the present invention to provide a solution to the problems described above with respect to applying additional viscous media to a substrate that has already been initially coated with viscous media by screen printing.
[0007]
These and other objects are achieved according to the present invention by providing a method and apparatus having the features defined in the independent claims. Preferred embodiments are defined in the dependent claims.
[0008]
According to a first aspect of the present invention, in the method of applying a viscous medium to a substrate, a step of screen printing a predetermined amount of the viscous medium at a predetermined position on the substrate, and a predetermined position at a predetermined position on the screen printed substrate. Additional injection of an additional amount of viscous medium.
[0009]
According to the second aspect of the present invention, in the apparatus for applying the viscous medium to the substrate, the screen printing means for screen-printing a predetermined amount of the viscous medium at a predetermined position of the substrate, and the predetermined position at the predetermined position of the screen-printed substrate. And an injection means for injecting an additional amount of viscous medium.
[0010]
According to a third aspect of the present invention, there is provided an apparatus for applying an additional viscous medium to a screen-printed substrate, comprising an injection means for injecting the additional amount of the viscous medium to a predetermined position of the substrate.
[0011]
According to a fourth aspect of the invention, there is provided the use of screen printing and subsequent jetting to apply a viscous medium to a substrate.
[0012]
According to a fifth aspect of the invention, there is provided the use of viscous media jets to apply additional viscous media to a screen printed substrate.
[0013]
In this application, the term “viscous medium” is interpreted as solder paste, flux, adhesive, conductive adhesive, or any other type of medium used to secure components to a substrate, "Is interpreted as printed circuit board (PCB), ball grid array (BGA) board, chip scale package (CSP), quad flat package (QFP), flip chip, etc. And The term "jetting" is a contact metering process such as "fluid wetting", where the viscous medium exits the metering tip, contacts and adheres to the substrate, and remains on the substrate when the metering tip is pulled apart In contrast, a fluid jet is used to form a droplet of viscous media and eject it from a jet nozzle onto a substrate, as described, for example, in published International Patent Application No. 99/64167. Note also that it should be interpreted as a non-contact metering process. Furthermore, the term “addition” refers herein to applying an additional viscous medium. That is, it is not an initial application.
[0014]
The present invention is therefore based on the advantageous concept of using additional jets to apply additional viscous media to a substrate that has previously been coated with viscous media by screen printing.
[0015]
By using jetting, some of the above-mentioned problems with screen printing are overcome. First, it is possible to apply a different type or kind of viscous medium than the one originally applied by spraying. By using jetting, the viscous media can be applied in any desired pattern, which is not possible with screen printing. Various heights of viscous media application can also be achieved by spraying. Also, injection is advantageous over conventional metering in that it is faster, more accurate and flexible. In fact, the use of conventional metering often presents an obstacle in that the cycle time in the overall component mounting process is increased compared to the use of injection. It has also been found that using jets it is possible to achieve smaller dots when using conventional metering.
[0016]
In addition, one of the major advantages gained using jets to apply additional viscous media to screen printed substrates is the ability to apply viscous media where it has already been applied. It is a thing. Thereby, there is no danger that the nozzle of an injection tool will be contaminated by the viscous medium already applied to the substrate, and the height of the applied viscous medium can be easily increased at a specific position.
[0017]
According to a particular embodiment of the invention, the result of applying a viscous medium to the substrate is inspected, and an application error is detected based on the inspection, and at least a part of the error is corrected, wherein the correction is Spraying additional viscous medium onto the substrate. That is, not only a predetermined additional amount of viscous medium is applied to the substrate by spraying, but also an additional amount of viscous medium determined to be necessary as a result of an error in normal viscous medium application.
[0018]
The inspection can be performed during screen printing and additional jetting of viscous media, after additional jetting of viscous media, or both. When performing an inspection between screen printing and additional injection, a predetermined additional injection is combined with a correction injection by determining the position and amount that require injection, or by performing additional injection and injection correction in order. be able to.
[0019]
A single injection means preferably performs both additional injection and injection correction, which reduces the physical complexity of the system. Alternatively, this is performed by a separate injection means.
[0020]
If the inspection is performed only after the additional injection, the correction can be performed on a separate machine. This shortens the overall viscous media application process cycle time, but increases the line length. If a separate machine is used for injection correction, error checking, evaluation and judgment are preferably performed on the same machine, but it is not necessary to do so.
[0021]
According to a further embodiment of the invention, the modification of the applied viscous medium also includes removing excess viscous medium. This is preferably performed only at specific locations on the substrate that have been found by inspection that too much viscous medium has been applied. This means that the amount of the viscous medium at any position, the height of the applied viscous medium, the deviation of the applied viscous medium from the intended position, or the viscous medium being applied to an unintended position.
[0022]
According to a further embodiment of the invention, after inspection of the substrate, an evaluation is performed to determine whether the number or degree of detected error is equivalent to a modification of the applied viscous medium. Such an evaluation can be performed regardless of whether the inspection is performed before or after the additional injection of additional viscous medium. That is, if a large amount of correction is required, it may be more economical to simply discard the substrate. This is of course determined by the type of substrate and the cost of the substrate. If the modification is deemed worthless, the substrate is preferably cleaned and reused for the applied viscous medium. On the other hand, when it is determined that the cleaning of the substrate is not economical, it is preferable to discard the substrate.
[0023]
Note that screen printing and subsequent jetting of viscous media is not limited to the use of one viscous media for both screen printing and jetting in this application. As a result, several different types and types of viscous media can be used. For example, screen printing is performed with a certain viscous medium, and then additional jetting is performed with another viscous medium. Additionally, subsequent injections, additional injections and / or modified injections can be performed in sequence with different types of viscous media. Second, multiple injection means may be used to avoid undesired mixing of different viscous media, or to avoid increased cycle time due to changes in viscous medium supply and possibly cleaning the injection means. preferable.
[0024]
These and other aspects, advantages and features of the present invention will be more fully understood from the following description of exemplary embodiments.
[0025]
Exemplary embodiments of the invention are described below with reference to the accompanying drawings.
[0026]
Detailed Description of Preferred Embodiments
In the block diagrams of FIGS. 1 to 3, thick arrows indicate the movement of the substrate 1 through the production line. The dotted box simply indicates that the means or device drawn in the box can be integrated into one machine.
[0027]
Referring to FIGS. 1-6, an exemplary embodiment of the present invention is illustrated. Specific means used for screen printing, jetting, application result inspection, solder paste removal, and component mounting are suitable means known per se in the art, and likewise Structural features can be used. Accordingly, detailed structural and functional descriptions for each individual means are omitted. Further, the viscous medium described in the following exemplary embodiment is a solder paste. However, the present invention is not limited to the use of solder paste. Conversely, any type of viscous medium can be used.
[0028]
Referring initially to FIGS. 1-4, a first exemplary embodiment of the present invention is illustrated. The substrate 1 is transferred to the screen printer 12 in step 100, where initial application of solder paste is performed in step 102. Next, the substrate 1 is transferred to the machine 16 at step 104, and additional injection of an additional amount of solder paste is executed at step 106. The amount, pattern, height, type, etc. of the solder paste applied to the substrate 1 are determined in advance. Therefore, there is no inspection if the screen printing result is executed before the additional solder paste is sprayed. After the additional injection step, the substrate 1 is transferred to the component mounting machine 18 at step 108 where the electrical components are mounted on the substrate 1. As an alternative, it may also include the step of inspecting the combined solder paste application, ie the final result of both screen printing and additional jetting.
[0029]
With reference now to FIGS. 2 and 5, another exemplary embodiment of the present invention is illustrated. This embodiment also includes inspection means 14 provided for inspecting the screen printing result. After screen printing in step 202, the substrate is transferred to the inspection means 14 in step 204, which performs the inspection in step 206. In order to perform additional injection, the inspection results are recorded and relayed to the means 16 '. With the information regarding the result of the inspection, the spraying means 16 ′ can also spray the necessary additional solder paste on the position of the substrate where the coating amount is insufficient due to some error in the initial screen printing. Therefore, the injection means 16 ′ is a means 16 ′ that combines additional injection and correction. Furthermore, according to this embodiment, the additional jet and correction means 16 ′ can also include means for removing an amount of solder paste from the substrate. According to this embodiment, removal is performed by suction of solder paste at selected locations on the substrate. If it is found by inspection that the substrate 1 is not corrected, the substrate 1 passes through the additional injection and correction means 16 ′ without taking any measures. Next, the substrate 1 is simply taken out of the production line before reaching the component mounting machine 18.
[0030]
The inspection means 14 is preferably integrated into the same machine as the additional injection and correction means 16 ′ and thus forms a combined inspection and correction machine 15. Next, the inspection means 14 can be used to inspect the results of the additional jets to further minimize coating errors on the substrate. However, the inspection means 14 can naturally be a separate machine.
[0031]
After the correction and additional injection in step 208, the substrate is transferred to the component mounter 18 in step 210.
[0032]
Finally, the block diagram of FIG. 3 and the flowchart of FIG. 6 illustrate yet another exemplary embodiment of the present invention. Here, the screen printer 12 and the inspection means 14 are incorporated into one machine 10. After the substrate 1 is screen-printed in steps 300 to 304 and the screen printing result is inspected by the screen printer and the inspection means 10, the substrate 1 is transferred to the additional jet and correction means 16 ′. The additional injection and correction means 16 ′ has the same function as the corresponding means 16 ′ of FIG. When the substrate enters the additional injection and correction means 16 ', said means 16' has received information regarding any necessary corrections to be performed on the substrate 1. Next, an additional solder paste is added in step 308 to correct the application error, and the substrate 1 is transferred to the component mounting machine 18 in step 310. Also in this case, if the inspection reveals that the substrate 1 has some errors due to screen printing and it is worth correcting, the substrate 1 is taken out of the production line. In this embodiment, this is done before the substrate 1 reaches the additional injection and correction means 16 '.
[0033]
As will be appreciated by those skilled in the art, the steps described above require a certain amount of processing, transport, and evaluation information. However, this can be performed by conventional processing means, which are not shown and will not be described further.
[0034]
Although the invention has been described above using exemplary embodiments thereof, modifications, alterations and combinations thereof, as would be understood by a person skilled in the art, are within the scope of the invention as defined in the appended claims. Can be executed.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an arrangement according to an alternative embodiment of the present invention.
FIG. 2 is a block diagram illustrating an arrangement according to an alternative embodiment of the present invention.
FIG. 3 is a block diagram illustrating an arrangement according to an alternative embodiment of the present invention.
FIG. 4 shows a flow diagram of the alternative embodiment shown in FIG.
FIG. 5 shows a flow diagram of an alternative embodiment shown in FIG.
6 shows a flow diagram of the alternative embodiment shown in FIG.

Claims (19)

In a method of applying a viscous medium to the substrate,
Screen printing a predetermined amount of viscous medium at a predetermined position on the substrate;
Additionally spraying a predetermined additional amount of viscous medium on a predetermined position of the screen printed substrate;
A method comprising the step of determining the predetermined position and a predetermined additional amount of the additional spraying step before the screen printing step. Inspecting the results of the screen printing and additional jetting;
Determining the screen printing and additional jetting errors based on the inspection;
A step to determine if correction is necessary,
2. Correcting at least a portion of the error if correction is necessary, the correction comprising supplementally spraying additional viscous media onto the screen printed substrate. Method. Inspecting the result of the screen printing before the additional jet;
Determining an error in the screen printing based on the inspection;
Determining whether a correction is necessary and, if necessary, correcting at least a portion of the error, the correction comprising supplementally spraying additional viscous media onto the screen printed substrate The method of claim 1.   The method of claim 3, wherein the supplemental injection is performed in connection with performing the additional injection.   The method according to claim 2, wherein the additional injection and the supplementary injection are performed by the same injection means. The correcting step comprises:
6. A method according to any one of claims 2 to 5, comprising the step of removing an amount of viscous medium from a position on the substrate. Determining whether the correction is necessary,
7. A method according to any one of claims 2 to 6, including the step of evaluating all the determined errors and determining whether the determined errors should be corrected.   The method according to claim 1, wherein at least one viscous medium applied by the additional jet is different from a viscous medium applied by screen printing. A device that applies a viscous medium to a substrate.
Screen printing means for screen printing a predetermined amount of viscous medium at a predetermined position on the substrate;
An apparatus for injecting a predetermined additional amount of viscous medium to a predetermined position of a screen printed substrate, and determining the predetermined position and the predetermined additional amount before performing the screen printing. Inspection means for inspecting the result of the screen printing and jetting;
Processing means for determining an error in the screen printing and jetting based on the inspection;
The correction means according to claim 9, comprising correction means for correcting at least part of the error, the correction means comprising jetting means arranged to supplementarily jet a quantity of viscous medium on the screen printed substrate. apparatus. Inspection means for inspecting the result of the screen printing;
Processing means for determining an error in the screen printing based on the inspection;
10. Correcting means for correcting at least a portion of the error, wherein the correcting means comprises spraying means arranged to supplementarily spray a quantity of viscous medium on a screen printed substrate. Equipment.   12. Apparatus according to claim 10 or 11, wherein the correction means comprises removal means for removing the viscous medium from the screen printed substrate.   13. The apparatus according to any one of claims 10 to 12, wherein the spraying means for spraying an additional amount of viscous medium to the predetermined position of the substrate and the supplemental spraying means are the same spraying means.   An apparatus for applying an additional viscous medium to a screen-printed substrate, comprising spraying means for spraying the additional amount of viscous medium to a predetermined position of the substrate, and before the screen printing, A device that determines the additional amount. Inspection means for inspecting the result of the screen printing and jetting;
Processing means for determining an error in the screen printing and jetting based on the inspection;
15. Correcting means for correcting at least a portion of the error, the correcting means comprising spraying means arranged to supplementarily spray a quantity of viscous media on a screen printed substrate. Equipment. Inspection means for inspecting the result of the screen printing; processing means for judging an error in the screen printing based on the inspection;
15. Correcting means for correcting at least a portion of the error, the correcting means comprising spraying means arranged to supplementarily spray a quantity of viscous media on a screen printed substrate. Equipment.   17. An apparatus according to claim 15 or 16, wherein the correction means comprises removal means for removing the viscous medium from the screen printed substrate.   18. An apparatus according to any one of claims 15 to 17, wherein the spraying means for spraying the additional amount of viscous medium to the predetermined position of the substrate and the supplemental spraying means are the same spraying means.   Use of viscous media jets to apply additional viscous media to screen printed substrates.

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